This section provides background information related to the present disclosure which is not necessarily prior art.
There are many needs and uses in the world in which a tether or leash or some kind of attachment means is used to flexibly connect two entities together. Some flexible attachment methods are quite common and readily recognized in widespread use such as a dog leash. Another application, not in wide spread use is a tow strap between two vehicles. Still another application even less well known by the general population is a safety harness to prevent falls from elevated positions.
Traditional leashes and tethers and other similar applications all suffer from a common problem, and that is at the moment the tether becomes taut due to the two entities at opposing ends of the tether moving apart the tether abruptly restricts relative movement of one or both entities. This abrupt restriction to movement can cause injury, hard jerks, personal discomfort, loss of balance, and/or damage to the tether.
The applications and uses of tether type devices and systems are expanding for everyday life activities, work environments, sporting activities, and leisure activities. There is a great need for an improved tether type device that imposes restrictive movement between two entities and yet prevents destructive forces acting upon either the tether and/or the entities connected to the tether device.
In applications where animals are tethered by a human for the purposes of recreation and/or training and/or restraint, it is a common place scenario when the animal jerks or lunges in such fashion as to cause the tether device to become taut causing injury to the person and/or the animal. In addition, sudden lunging scenarios with the animal and tether device can cause the tether device to fail in response to the huge potential impact forces that can be generated by an animal's actions. Such a failure in the tether device often results in the animal getting loose presenting a danger to itself and/or others nearby.
There are a number of references trying to address this problem in selected applications, however, the prior examples fall short of satisfactorily resolving the issues at hand and usually at best are very limited in their application.
In the sport of water skiing devices such as U.S. Pat. No. 6,119,617 reveal a stand pipe fixed to a boat which includes a spring system housed inside to give the ski rope a spring give-feel to the skier. One problem with this type of device is that it is hard mounted to the boat and offers no flexibility for alternate applications. Another problem with this device is that the spring element is oriented essentially transverse to the direction of pull of the ski rope which inhibits and/or minimizes sensitivity and response time for the skier trying to remain upright and balanced. Another problem is that spring devices have a relatively constant spring rate which is not adjustable or tunable to the users needs for different spring rates during use of the product.
In the sport of surfing, United States Patent Application Publication 2006/0141879-A1 presents a leash device connecting a surf board to the user designed to prevent being tangled. One problem with this design is that the proposed weight increases drag in the water at a distant point of the leash and further adds a measure of mass increasing momentum whenever the user is separated from the surf board causing the inevitable taut jerk of the leash to be even more violent than it might have been otherwise.
U.S. Design Pat. D-571,059-S proposes a tube with a spring device housed inside. The spring housing assembly is designed to be connected between a dog collar and a leash to absorb shock. One problem with this type of device is that the spring response time is very slow compared to the response time of a dog as it lunges suddenly such that the spring does not have time to absorb shock fast enough to prevent it being transferred through the assembly to the person. Another problem with this type of device is that the weight of the assembly next to the dog collar and its relative size is bulky and distractive to the animal. Another problem is that the device has a relatively constant spring rate and does not allow a means to adjust the spring rate of shock absorption for different scenarios.
United States Patent Application Publication 2009/0000568-A1 proposes a shock absorbing elastic element with loops on the ends to allow a normal known leash to be wound around the elastic element in a spiral candy cane like orientation. One problem with this device is that upon stretching the elastic element the leash spirals essentially unwind trying to return to a straight leash, which does absorb some shock—the first time. However, after being unwound substantially, the leash has little or no means to wind back up and it therefore remains in a somewhat unwound state rendering further shock absorbing capabilities dramatically impaired. Another problem with this device is that the leash spirals and twists around as the elastic element stretches and the leash unwinds, which causes the entire leash to become twisted like a swizzle stick. Because the leash does not wind itself back up, the leash remains in a twisted condition. Even if the connection of the leash ends includes a swivel joint the friction of the swivel components is greater than the force required to unwind the leash spiral around the elastic element and therefore based on principles of least force resistance the swivel joints act as though they are welded solid.
Very few additional devices exist in the market place to address this problem with any success in any of the fields of application for the subject invention. Therefore, the subject invention overcomes these shortcomings and addresses the needs of the consumer in various applications.